As is known, lamination of panels, particularly panels for manufacturing furniture components, by means of a lamina of synthetic material, by veneering or the like, is generally performed by heating and causing the adhesion of the facing lamina to the panel inside a press.
In many cases, the lamina must cover one of the largest faces of the panel and the lateral faces that are adjacent to such larger face.
Because of this requirement, the panels to be laminated are generally fed to the press by arranging them on a tray, which supports the panel by means of a plurality of pins. More particularly, the panel is rested, on a substantially horizontal plane, on the tray and is supported by a plurality of pins which have a substantially vertical axis and make contact with its lower face, which constitutes one of the larger faces of the panel and lies opposite the face that is designed to be laminated together with the lateral faces.
In order to allow the lamina used for lamination to cover completely the lateral faces, the pins with which the tray is equipped generally can be arranged in two positions: a raised position, in which they make contact with the lower face of the panel, and a lowered position, in which they are spaced below the lower face of the panel, which is supported by the pins which instead are in the raised position. The pins that are completely covered by the panel are moved manually or mechanically or kept in the raised position before or after the deposition of the panel on the tray, while the pins that are designed to be covered only partially or not covered at all by the panel are moved into or kept in the lowered position. In this manner, the panel rests on the pins in the raised position with its lower face except for a region which lies proximate to the edge of the panel, so that the lamina, as a consequence of the pressure applied by the press, optionally assisted by suction applied to the lower face of the lamina, can adhere to the upper face and to the lateral faces of the panel.
A tray of this kind is disclosed in EP 1,160,074 by the same Applicant.
The tray disclosed in this patent is arranged on a substantially horizontal plane and is used to insert and remove the panels or other objects to be laminated in the press. More particularly, the tray has a plurality of seats which have a substantially vertical axis and each of which accommodates a pin provided with a head which protrudes from the upper face of the tray. Such pins define, as a whole, with their heads, a supporting surface for the lower face of the panel to be laminated. The pins can move individually on command, along the axis of the corresponding seat, in order to pass from a raised position, in which they are adapted to make contact with the panel and support it, to a lowered position, in which they are spaced downwardly from the panel. For each pin elastic means are provided which co-operate with the pin and the corresponding seat so as to retain the pin in the raised position. Such elastic means are flexible in order to allow the passage of the corresponding pin from the raised position to the lowered position or vice versa.
When it is necessary to pass from the lamination of one type of panel to another type of panel which differs in terms of dimensions and/or shape, it becomes necessary to perform the so-called “reset” of the position of the pins in the tray used previously. This resetting operation consists substantially in moving all the pins into the lowered position or raised position so as to be able to then perform a selection operation, by way of which only the pins whose head is designed to be covered completely by the new panel to be laminated are moved into or kept in the raised position.
In the European patent cited above, among the several methods for preparing the tray for positioning a different type of panel or panels, the suggestion is given to start with all the pins arranged in a position which is intermediate between the raised position and the lowered position and to act by way of selection means exclusively on the pins which are covered or will be covered completely by the panel or panels, so as to produce their transition to the raised position, in which they are kept by the action of the elastic means.
In using trays of this kind, it has been found that it is preferable to prepare the tray with the panel or panels to be fed to the press already resting on the pins. In this preferred operating condition, the transition of the pins that are completely covered by the panel or panels from the intermediate position to the raised position lifts the panel or panels. Since lifting of the pins that are completely covered by the panel or panels does not occur simultaneously but in succession by rows of pins, unwanted displacements of the panel or panels can occur with respect to the tray, penalizing the precision of positioning and possibly compromising the good outcome of the lamination operation.
For this reason, the need is felt to be able to prepare the tray by starting the operation with all the pins in the raised position and then causing the transition of the pins that are not completely covered by the panel or panels from the raised position to the lowered position.
This operation, as suggested in the above cited European patent, can be performed by acting manually or mechanically on the head of the pins to be lowered. In the case of automated action, the above cited European patent suggests the use of a bar which is moved above the tray and supports a plurality of pressers, which can be operated individually in order to act exclusively on the pins that must be lowered.
The adoption of a bar of this kind does not entail problems if the selection of the pins is performed before resting the panel or panels on the tray, but it is unquestionably a source of problems when one wishes to prepare the tray when the panel or panels is or are already rested on the tray.